The primary objective of the proposed studies is to understand the role of complex carbohydrates in normal nervous function and the dysfunction resulting from genetic or environmental factors which results in mental retardation. One system to be used is the cloned mouse neurotumor cell line, specifically neuroblastoma, astrocytoma and Schwannoma. Each of these has a specific glycosphingolipid (and possibly also a specific glycoprotein and glycosaminoglycan composition) which can be related to that in normal mouse brain. We will study factors such as hormones, neurotransmitters, cyclic nucleotides and metal ions which could influence the metabolism of those compounds during development and differentiation of the nervous system. A second project will attempt to evaluate the role of lipoprotein-glycolipid complexes in cell-cell interaction and a third project will be specifically directed towards understanding the biological role of the complex carbohydrate chain-terminating sugar L-fucose (6-deoxy-L-galactose).